Selective flotation of minerals



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' and useful Improvements in- Selective Flo tation of Minerals; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains, to make and use the same.

This invention relates to the selective flotation of sulfide minerals, and more particularly to the separation of lead and zinc sulfides by selective flotation.

The invention is basedupon the discovery that lead sulfide can be selectively floated from zinc sulfide in a slightly alkaline solution if a small amount of a soluble sulfite, such as sodium sulfite, is present in the ore pulp, and if a suitable flotation agent or agents, operative in a slightly alkaline pulp, are also present. v

Where the ore pulp is itself slightly alkaline in reaction, the addition of further amounts of alkaline reagents may be un necessary. Where, however, the ore pulp is slightly acid, for example, due to'oxidation of a small amount ofthe sulfide mineral, the pulp can be given a slight alkalinity by the addition of a suitable alkaline reagent, such as lime, which I regard as particularly advantageous, although other alkaline reagents can be used, such as sodium sulfide, sodium carbonate or soda ash, caustic soda, etc. The lime can thus be incorporated thioearbanilid, with sodium sulfite, and with some alkaline substance, such as' lime, to make the pulp very transferred to a with the ore pulp during the grinding operation, in such amount as to make the pulp very slightly alkaline.

.Various agents for promoting the flotation, which act as flotation agents in a slightly alkaline pulp, can be used. l: have found thiocarbanilid partimilarly advantageous hen used together with an agent having good frothing qualities.

The ore canthus be ground with the in suflicient amount slightly. alkaline, and the pulp can then be Callow pneumatic cell, and subjected to flotation therein with the addition of a small amount of an agent having good a lenses, or SALT LAKE CITY, UTAH, ASSIGNOB T0 mn'rans comrm, or NEW YORK, N. Y., A

j Application filed January 28, 1921.

'banilid inxylidin, can

flotation cell, such asfa;

aerate? it We earner sa eanncovner ooaroaa'rron or name.

SELECTIVE FLOTATION 0F MINERALS.

Serial Il'o. 440359.

frothing qualities, such as slightly acidus lated aldol.

I have found that sodium sulfite, in sucha slightly alkaline pulp, very largely prevents the zinc sulfide from, floating, but that the de ressing eifect upon the lead sulfide is re atively small, so that the sulfide will be floated without any appreciable flotation of zinc sulfide. ingly, a relatively high gradelead sulfide concentrate can thus be obtained, low in zinc. 1

7 After the lead sulfide has thus been selectiv'ely floated, the orepulp is treated to decrease the amount of soluble sulfite remaing therein. For example,.the tails from the lead sulfide flotation, can be dewatered to remove a considerable part of thewater therefrom, together with a corresponding amount of the sulfite, or the tails can, be otherwise treated to decrease the amount of sulfite therein. When the tails are dewatered, for example, to say about 35% solids, a suflicient amount of fresh watercan be added to bring the pulp to'proper dilution and further amounts of flotation agent or agents added thereto. advantage to add a further amount of alkali, such as sodium carbonate, and also lead did

so It is ofa small amount of copper sulfate to the pulp. So also, a further amount of flotation agent, such as a solution of thiocarbe added, and the pulp subjected to a further flotation operation and the flotation continued until the zinc sulfide ceases to come over. or untilthe greater part of the zinc sulfide has been floated, and the amount of trate can-be brought about by tabling to form separate lead and zinc concentrates, and the lead concentrate so obtained can be added tothe flotation lead concentrate.

The quantities of reagents used in the practice of the process can be somewhat varied, depending upon the particular are,

etc. Usually only a small amount of soluable sulfite, such as sodium sulfite, will'be iron sulfide loecomes. undesirable in amount as a cofn- Lee,

I however, have in pulps which have a decidely alkaline re-' action. Accordingly, only a slight alkaline reaction will usually be desirable. So also, there will ordinarily be no advantage in unnecessarily increasing the amount of sodium siilfite, as only a small amount is required to prevent the flotation of the zinc and iron sulfides, While permitting the flotation of the lead sul .fide. ll have obtained treatment of certain lea -zinc ores,jvvith the use of about 1 pound of lime per ton of ore,

' ahoutg pound thiocarbanilid per ton of ore and about 1 pound sodium sulfite per ton of ore, adding all of these reagents tothe mill and grinding them with the ore; although the amounts of these various reagents are capable of some variation. The nature and amount of the agent added to improve the trotn formation is aiso capable of variation.

Acid treated aldol is mentioned as an agent suitable for this purpose inconjunction with tl'iiocarbanilid which has marked selective properties. 7

Afterthe flotation of the lead sulfide, as

above described, the remaining pulp can then Gil be subjected to a dewatering operation to remove as much as possible of the sodium sulfite from the water before attempting to floatthe zinc. After the pulp has thus been dewatered and again brought to the proper dilution, further amounts of agents promoting the flotation of the zinc sulfide can be added. I have thus found it of advantage to add a. small amount of an alkaline substance, such as sodium carbonate, as Well as a small amount of copper sulfate, for ex ample, using about 5 pounds of sodium oarbonate and 1 pound of copper sulfate per ton of orignial ore, and thoroughly mixing these reagents with the ore pulp before adding the flotation agent. As a notation agent for the flotation of the zinc sulfide'I have used with advantage a solution of thiocarbanilid .in

i xylidin, containing about 15% thi'ocarbanilid and xylidi/n by weight, and using 0.4

pounds of thesolution per ton of ore I have used larger amounts of sodiumcarbonate and copper sulfateibut with the particular ores treated, such larger amounts were not found to be correspondingly more advantageous; While the omission of these two reagents resultsin the production-of a lower grade concentrate.

good results, in the Means? The process of the present invention is applicable not'only to theselective separation of lead and zinc sulfides by flotation, but also to the selective separation of other sulfides from each other.

I claim:

1. The method of effecting the selective flotation of sulfide minerals, which comprises subjecting a slightly alkaline pulp, containin a small amount of a solublesulfite therein, to a flotation operation. I

2. The method of efl'ecting the selective flotation of lead sulfide from ores containing zinc sulfide, which comprises subjecting a slightly alkaline ore pulp, containing 50 a small amount of a soluble sulfite, to a flotation operation.

8; The method of effecting the selective flotation of sulfide minerals, which comprises adding to the mineral pulp a small 8 amount of alkaline substances sutficient to give the pulp a slight alkaline reaction and a small amount of a soluble sulfite, and subjecting the resulting pulp to a flotation operation.

e. The method of efl'ecting the selective flotation of lead sulfide from ores containingzinc sulfide which comprises adding to the ore pulp a small amount of an alkaline substance to give the pulp a slight alkaline reaction, adding a small amount of a soluble sulfite, together with a suitable flotation agent, and subjecting the resulting pulp to a flotation operation.

5. The method of efiecting' the selective flotation of lead sulfide from ores containing zinc sulfide, which comprises adding to the ore pulp a small amount of an alkaline substance to give the pulp a slight akaline reaction, together with a small amount of a 10s soluble sulfite, a small amount of thiocarbanilid and an agent having good frothing qualities, and subjecting the resulting pulp to a flotation operation.

6. The method of effecting the selective no flotationof sulfide minerals, which comprises subjecting a slightly alkaline plup containing a small amount of a soluble sulfite therein to a flotation operation to remove certain of the sulfides, reducing the amount of soluble sulfide remaining in the pulp and subjecting the pulp to a further flotation operation for the flotation of other sulfides. f 7. The method of efl'ecting the selective flotation of lead and zinc sulfides which comprises subjecting a slightly alkaline pulp containing a small amount of a soluble sulfite to a flotation operation for the production of a leadv sulfide concentrate, decreasing the amount of soluble sulfite in the remaining ore pulp to an amount permitting flotation of zinc sulfide, and subjecting the ore pulp to a further flotation operation.

antenna 8. The method of efiecting the selective flotation of lead and zinc sulfides, which comprises subjecting a slightly alkaline ore pulp containing a small amount of a soluble sulfite to a flotation operation for the production of a lead concentrate, treating the remaining pulp to reduce the amount of soluble sulfite therein to permit flotation of zinc sulfide, adding a further amount of alkali and of a flotation agent and subjecting the pulp to a further flotation for the production of a zinc concentrate.

9. The method of efiecting the selective flotation of lead and zinc sulfides which comprises subjecting a slightl alka ine ore pulp in the presenceof a solu le sulfite to a flotation operation for the production of a lead sulfide concentrate, removing a considerable portion of the sulfite from the ore pulp, adding thereto a small amount of an alkaline substance and a small amount of copper sulfate together with a. flotation agent and subjectin the pulp to a' further flotation operation or the treatment of a zinc concentrate.

10. The method of eflecting the selective flotation of lead and zinc sulfides, which comprises adding to the ore pulp a small amount of an alkaline substance to give the pulp a slight alkaline reaction, adding a small amount of a soluble sulfite, asmall amount of thiocarbanilid and a small amount of a substance having good frothing qualities, subjecting the pulp to a flotation operation for the production of a lead concentrate, treating the remaining pulp to reduce the amount of soluble sulfite therein, adding a further amount of an alkaline substance and of a flotation agent thereto, and subjecting the pulp to a further flotation operation for the production of a zinc con-- centrate.

11. The method of eflecting the sepa a slightly alkaline ore.

tion operation for the production of a lead concentrate,- decreasing the amount of soluble .sulfite in the remaining pulp to per: mit the flotation of zinc sulfide, subjecting the pulp to a further flotation operation for the production of a zinc concentrate, and subjecting the zinc concentrate to a tabling operation to efi'ect the separation of as small amounts of lead sulfide therefrom.

In testimony whereof I a 5' s1 GERT A ;:i GIG. 

